If f, g, h are real functions defined by,
and h(x) = 2x2 – 3, then find the values of (2f + g – h)(1) and (2f + g – h)(0).
Given,
and h(x) = 2x3 – 3
We know the square of a real number is never negative.
Clearly, f(x) takes real values only when x + 1 ≥ 0
⇒ x ≥ –1
∴ x ∈ [–1, ∞)
Thus, domain of f = [–1, ∞)
g(x) is defined for all real values of x, except for 0.
Thus, domain of g = R – {0}
h(x) is defined for all real values of x.
Thus, domain of h = R
We know (2f + g – h)(x) = (2f)(x) + g(x) – h(x)
⇒ (2f + g – h)(x) = 2f(x) + g(x) – h(x)
Domain of 2f + g – h = Domain of f ∩ Domain of g ∩ Domain of h
⇒ Domain of 2f + g – h = [–1, ∞) ∩ R – {0} ∩ R
∴ Domain of 2f + g – h = [–1, ∞) – {0}
i. (2f + g – h)(1)
We have
ii. (2f + g – h)(0)
0 is not in the domain of (2f + g – h)(x).
Hence, (2f + g – h)(0) does not exist.
Thus, and (2f + g – h)(0) does not exist as 0 is not in the domain of (2f + g – h)(x).